Photolithography is the process by which semiconductor circuitry is patterned on a substrate such as a silicon wafer. A photolithography light source provides the deep ultraviolet (DUV) light used to expose a photoresist on the wafer. DUV light is a range of light on the violet side of the color spectrum, beyond what the human eye can see. For example, DUV light can be light having wavelengths that range between about 100 nanometers (nm) to about 400 nm. DUV light for photolithography can be generated by excimer light sources. Often, the light source is a laser source and the pulsed light beam is a pulsed laser beam. The light beam is passed through a beam delivery unit, filtered through a reticle (or mask), and then projected onto a prepared silicon wafer. In this way, a chip design is patterned onto a photoresist that is then etched and cleaned, and then the process repeats.